> On 13 Jul 2022, at 19:05, Bruno Voisin <bvoi...@icloud.com> wrote: > > Overleaf has a very nice technical article on TeX's support of emojis > > https://www.overleaf.com/learn/latex/Articles/An_overview_of_technologies_supporting_the_use_of_colour_emoji_fonts_in_LaTeX > > discussing in detail why XeTeX doesn't support them (ie lack of support of > raster-based OpenType colour fonts).
Possibly the following, taken from the Overleaf article, will challenge programmers more directly: > The real cause of XeTeX’s failure > > The error messages provided by XeTeX partially obscure the actual cause of > the problem: OpenType colour fonts, particularly raster-based variants, are > not supported by XeTeX. In reality, XeTeX (Kpathsea) can find the Noto Color > Emoji font but XeTeX cannot load that font and is unable to initialize its > internal font-data tables which are required to use it for typesetting. > Internally, XeTeX starts the process of loading the font and tests it for > “scalability” (using FreeType’s “definition” of “scalability”) but that test > fails and XeTeX issues a standard, arguably misleading, TeX engine error > message. > > TeXnical note > > XeTeX’s processing of NotoColorEmoji.ttf was investigated by compiling a > debug version of the XeTeX executable. The Eclipse IDE was used to set a > breakpoint on the XeTeX function creatFontFromFile(filename, index, > pointsize) to step through the code and observe the subsequent processing. Bruno
